Phosphonium salts



United States Patent 3,364,245 PHOSPHSNIUM SALTS Martin Grayson, Norwalk, Patricia Tarpey Keough, Ridgefield, and Michael McKay Ranhut, Norwalk, (301111., assignors to American Cyanamid Company, Stamford, -Conn., a corporation of Maine No Drawing. Continuation-impart of application Ser. No. 344,224, Feb. 12, 1964. This application Sept. 8, 1966, Ser. No. 577,829

2 Claims. (Cl. 260-448.2)

ABSTRACT OF THE DISCLOSURE An organophosphorus compound of the formula:

9 a nza romoms ax wherein R R and R are alkyl C -C substituted alkyl C -C cycloalkyl, phenyl, substituted phenyl, or naphthyl, said substituents for alkyl being lower alkoxy or cyano and said substituents for phenyl being lower alkyl or halogen; X is halogen; and R is trialkylsilylmethylene, wherein alkyl is C -C 09 9 R R R P XCHzOHzOH R R R PcHzCHzOH-X 65 G R R R P CHzCHzOHX esterifying agent R R R each representing, as will be seen hereinafter, alkyl, cycloalkyl and aryl; X representing halogen or tetraphenyl borate; and Y representing the residue of an acrylating or esterifying agent. The following is a typical embodiment of generic Equations A and B, above:

6B 9 (n-CLHQaPCHzCHzOH-Br CHaCOCl The trialkyl-, tricycloalkyl-, and triaryl-Z-acetoxyethylphosphonium salts prepared as above may, in turn, be converted to their corresponding vinylphosphonium salts according to the following general equation:

69 9 base 9 6 (G)R R R PCHzCH2OY-X R R R PCH=CH2 X in which R R R Y and X are the same as above.

The following is a typical embodiment of Equation C, above:

Patented Jan. 16, 1968 ice More specifically, in generic Equations A, B and C, above, R R and R each represent alkyl C C substituted alkyl C C cycloalkyl, and aryl; X represents halogen, such as bromo, chloro and iodo, and tetraphenyl borate; and Y is Equations B and -C represents the residue of an acylating agent as shown in the specific embodiments, supra.

Typical tertiary phosphine reactants are the following: trimethylphosphine, triethylphosphine, tripropylphosphine, tributylphosphine, tripentylphosphine, trihexylphosphine, triheptylphosphine, trioctylphosphine, trinonylphosphine, tridecylphosphine, triundecylphosphine, tridodecylphosphine, tritridecylphosphine, tritetradecylphosphine, tripentadecylphosphine; trihexadecylphosphine, dodecyldiethylphosphine, dioctylpropylphosphine, diethylbutylphosphine, butylethylhexylphosphine, tri(2 methoxypentyl)phosphine, tris 2 cyanoethylphosphine, diethyl-2-ethoxyheptylphosphine, tricyclopropylphosphine, naphthylphosphine, trixyllphosphine, tritolylphosphine, tris(paraethoxyphenyl)phosphine, tris(para-chlorophenyl) phosphine, tris (2-chlorophenyl)phosphine, tris(3-brom0- phenyl)phosphine, and the like.

Typical esterifying agents follow: lower alkanoic anhydrides, such as acetic anhydride, propionic anhydride, butanoic anhydride; lower alkanoic acids, such as formic acid, acetic acid, propionic acid, butanoic acid; acylating (crclg alkanoyl) halides, such as acetyl chloride, propionyl bromide, butyryl iodide, octanoyl chloride, dodecanoyl bromide, stearyl chloride, hexanoyl bromide; isopropenyl acetate; aryl sulfonyl halides, such as paratoluenesulfonyl chloride, phenyl sulfonyl bromide, 2,4- dimethylphenylsulfonyl chloride; alkyl (lower) chloroformates, such as ethylchloroformate, butylchloroformate; alkyl (lower) carbonates, such as diethylcarbonate, dipropylcarbonate, dibutylcarbonate; ketene; dimethyl sulfate; nitrosyl chloride; and trimethyl phosphate.

In Equation C, above, typical suitable inorganic and organic bases are: alkali metal hydroxides, such as sodium hydroxide, potassium hydroxide, lithium hydroxide; alkali metal carbonates, such as sodium carbonate, potassium carbonate, lithium carbonate; alkaline earth metal hydroxides, such as magnesium hydroxide, barium hydroxide, calcium hydroxide; alkaline earth metal carbonates, such as magnesium carbonate, barium carbonate, calcium carbonate; activated alumina; and quaternary ammonium hydroxides, such as tetraalkyl (lower) ammonium hydroxides, including tetramethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabenzylammonium hydroxide; and basic ion exchange resins.*

The reaction in Equation A hereinabove is carried out at a temperature in the range of 30 C. to 250 C., preffer-ably 60 C. to 180 C. The Equation B reaction, above, is best carried out at a temperature in the range of 5 C. to C. As to Equation C, above, this reaction is .generally carried out at a temperature in the range of 20 C. to C., preferably 50 C. to 150 C.

Each of these three reactions may be carried out at atmospheric, sub-atmospheric or super-atmospheric pressure; preferably, however, reaction is carried out at atmospheric pressure. By the same token, the ratio of the reactants in each of Equations A, B and C is not critical, an excess of either reactant, in each equation, with respect to the other being suitable. In Equation B, however, an excess of about 10% by weight of the acylating agent relative to the phosphonium salt reactant is preferred. Generally in Equations A and C stoichiometric amounts of the reactants are employed.

The reactions of Equation A, above, are best carried out in the presence of an inert organic solvent, i.e., a

*Typical are: polymeric quarternary ammonium salts, e.g., polymeric trnuethylbenzyl ammonium chloride, etc.

substantial degree, are dimethoxyethane, dioxane, di-

methylformamide, diglyme, acetonitrile, ethylacetate, tetrahydrofuran, and other like linear and cyclic ethers, acetate esters (lower, alkyl).

Alternatively, it has been found pursuant to the instant discovery that the products of Equation A, above, may be converted directly to the products of equation C, thusly, D

in the presence of any base given above for Equation C and at a temperature in the range of 100 C. to 250 C. As in Equation C, a solvent of the type given hereinabove for Equation C is suitable and herein contemplated. If desired, the reaction may be carried out in the presence of a dehydrating agent, such as a siliceous agent including silica (e.g., silica gel), silica-alumina, and the like, in which other inert organic solvents are also suitable, e.g., aromatic hydrocarbons, such as toluene, benzene, xylene, cymene, and the like, methylene chloride, ethylene chloride, etc. 1

The products of Equations A, B, C and D'above are useful as fire retardants in plastics, e.g., from 0.5 to 30' parts by weight of any one of above compounds when incorporated into 100 parts by weight of a thermoplastic polymer material, such as polyethylene, polypropylene, polystyrene, polyacrylate, polymethyl-methacrylate, or the like, provides enhanced fire retardance to the polymer material upon exposure to an open flame.

While the following examples specify certain details as to certain embodiments of the present invention, it is not intended that these details impose unnecessary limitations upon the scope of the instant discovery, excepting of course that these limitations appear in the appended c amis.

Example I.--Tributyl-Z-hydroxyethylphosphonium tetraph enylbarate Tributyl-2-hydroxyethylphosphonium bromide, obtained from combining tributylphosphine and 2-bromoethanol in 1,2-dimethoxyethane and refluxing under nitrogen, is dissolved in water and treated with excess 0.1 N sodium tetraphenylboron. The resulting precipitate is filtered and recrystallized from ethanol to yield product tri butyl-2-hydroxyethylphosphonium tetraphenylborate' with melting point 124 C.125 C. Analysis of product (foundz C, 80.03; H, 9.00; P, 5.35. C H O requires: 0, 80.55; H, 9.25; P, 5.47%

As is evident from this example, the halide salts of Equation A may be converted, in situ or after recovery thereof, to the corresponding tetraphenylborate salts.

Example II.Trz'butyI-Z-acetoxyethylphosphonium bromide 1,2-dimethoxyethane (275 milliliters), freshly distilled from calcium hydride, 2-bromoethanol (133 grams, 1.06 moles), and tributylphosphine (204 grams, 1.01 moles) are combined under nitrogen and refluxed at 85 C. overnight with stirring. A heavy oil forms within an hour. Isopropenyl acetate (320 grams, 3.2 moles) and 48% HBr (3 drops) are slowly added to the reaction mixture which is then refluxed 18 hours. Volatile components are removed in vacuo at 70 C. Product (372.5 grams; 99.9%

yield) remains as a thick hygroscopic oil, which could be forced to crystallize by stirring in a'benzene-petroleum' ether (boiling point 30 C.60 C.) mixture. Crystalline tributyl-2-acetoxyethylphosphonium salt is obtained from part of the oily product by freeze drying a benzene solution of the oil.

Example III.Tributyl-Z-acetoxyethylphosphonium te traphenylborate Tributyl-2-acetoxyetl1ylphosphonium bromide oil (16.2 grams produced as in Example H, above) is dissolved in water and treated with sodium tetraphenylboron (15 grams) dissolved in water. A white precipitate appears which is filtered and recrystallized from ethanol containing enough acetonitrile to cause solution at the boiling point of themixturec Tributyl-Z-acetoxyethylphosphonium tetraphenylborate (16.7 grams) is obtained with melting point of 177 C.-179 C. Analysis of product (found: C, 76.65; H, 8.83; P, 5.24. C H O BP requires: C, 78.93; H, 8.94; P, 5.10%).

Example I V.--Triphenyl-2-acetoxyethylphosphonium iodide 2-iodoethyl acetate is prepared from the nucleophilic exchange reaction of sodium iodide and Z-chloroethylacetate in refluxing acetone under nitrogen (boiling point 86 C.90 Cat 33 milliliters mercury). Triphenylphosphine (7.35 grams) 'is reacted with '2-iodoethylacetate (24 grams) under nitrogen with stirring at C. for 4.5 hours. The excess 2-iodoethylacetate is distilled 05 in vacuo. Crude, brown crystalline product (14.20 grams) is obtained by washing oily residue with ether. :It is washed with ether, ethyl-acetate, and acetone andrecrystallized from acetonitrile to give product (7.90 grams) with melting point 161 C.l63 C. Analysis of product (found: C, 55.16; H, 4.80; I, 26.77; P, 6.45. C H O IB requires: C, 55.47; H, 4.66; I, 26.66; P, 6.51%).

Example IV represents still another embodiment of the present invention wherein the product salts of Equation B, above, are prepare-d directly from the reaction of a 2-haloethyl acetate with atertiary phosphine of the type contemplated herein.

The process of Example IV, above, may be carried out using any of the tertiary phosphine reactants contemplated herein and the corresponding tri-substituted-Z- acetoxyethylphosphon-ium halide produced and recovered,

according to the following equation ea R R R P XCHZCHzOO-CH: R R R POHzCHzOY-X wherein R R R X and Y have the meanings given hereinabove in Equations A and B.

Equation E is best carried out at a temperature in the Tables A, B, C, D and E, which follow, correspond to Equations A, B, C, D and E, respectively. The examples in Tables A and B are carried out essentially as in Examples I and II, respectively, supra, excepting of course as shown in Tables A and B. The examples in Table C are carried out essentially as in Example LX, infra, excepting of course as shown in Table C. Likewise, the products of Table D are recovered essentially as in Example LX, infra. The examples in Table E are carried out essentially as in Example IV, supra, excepting of course as shown in Table E.. a

TAB LE D e 6 base 69 9 R1R2R3POH2CH2OH'X R R R PCH= CHz-X Product of Temp., Dehydrating 500 Milliliters No. ExIaImple Base 0. Agent of Solvent Product 120 Silica gel Vinyltributylphosphonium chloride.

Silica-alumina Activated alumina Vinyltridodecylphosphonium chloride. Vinyltrihexadecylphosphoniurn chloride. Vinyldiethyl-Z-ethoxyethylphosphonium chloride. Vinyltricyclohexylphosphonium bromide. Vinyldiphenylnaphthylphosphonium iodide. Vinyltriphenylphosphonium iodide.

. Vinyltri(para-chlorophenyl)phosphonium chloride.

Vinyltri(para-tolyDphosphonium chloride.

1 Finely-divided particulates. 2 Finely-divided particulates.

TABLE E Example Temp.,

No. R R R=P+ g C. Solvent Product XCH2CH O OBT:

Tridodeeylphosphine X=Br Reflux. Ethanol '1gdodegyl-Z-acetoxy-ethylphosphonium roim e.

11 Trieyclohexylphosphine X=I 85 Acetonitrile... Tricyclohexyl-2-acetoxy-ethylphosphonium oidide.

12 Tris(Z-chlorophenyD-phosphine X=Cl Reflux Acetone Tris(Z-chlorophenyl)-2-acetoxyethylphosphonium chloride.

13 Tri(2-methoxypentyD-phosphine X=I Dioxane 2-acetoxyethylphosphonium iodide.

By finely-divided particulates in Table D is intended 28 to 200 mesh. Larger or smaller particulates are likewise within the purview of the instant discovery.

Example LX.-Tribuzylinvylphosphonium bromide Tributyl-2 acetoxyethylphosphonium bromide (23.7 millimoles) is dissolved in 1,2-dimethoxyethane (25 milliliters) and sodium carbonate (5.0 grams, 47 millimoles) is added. The mixture is stirred at reflux under nitrogen for 8 hours. The solid is filtered off and washed with hot 1,2-dimethoxyethane. The combined filtrates are evaporated to leave 'a semi-solid residue. Recrystallization from ethyl acetate yields product tributylvinylphosphonium bromide (3.3 grams, 10.7 millirnoles, 45% yield with melting point 148 C.-I50 C.) Further recrystallization from ethylacetate-acetonitrile raises the melting point to 151.5" C. to 152.5 C.

Pursuant to the present discovery, the products of Tables B, C, D and E, hereinabove, may be converted to their corresponding sulfur-containing derivatives by reaction with s-ulfhydryl (e.g., an alkyl mercaptan, an alkane dithiol, a benzenetl'n'ol, a dialkylphosphorodithioate, an 0,0- dialkylphosphorodithiolate, and the like) at a temperature in the range 20 C. to 200 C. Table F, G, H which follows illustrates this reaction, the examples in said table being carried out essentially as in Example L)Q(VI, infra, excepting of course as specified in the table:

l 5 Example LXX VI ll atrina-cutouts? (00111921 136 is obtained in nearly quantitative yield as a viscous syrup. Obviously, from Tables F, G, H, the symbols R R R Y and X have the meanings given hereinabove in corresponding Equations A, B, C, D and E. The remain- 4 ing symbols in Equations F, G and H of Tables F, G, H

have the following meanings:

R represents alkyl or alkylene having from 1 to 12 carbon atoms; benzyl; trialkylsilyl in which the alkyl moiety has from 1 to 8 carbon atoms; benzene; toluene, xylene; and 2-naphthylene.

n is selected from 1 and 2.

A and A each represent lower alkyl and lower alkoxy.

Q and Q each represent H,lower alkyl, or, when taken together, the residue of the; phenyl radical.

Z representsS or 0.

As is evident from Tables F, G, H, above,,the reactions,

contemplated therein using 2-acetoxyethylphosphonium salts are carried, out in the presence of a base of the type illustrated hereinabove for Equation C. By the same token, the vinylphosphonium salt reactants of Equations F, G and H, respectively, of Tables F, G, H may be reacted as shown in said tables using or omitting a base. Furthermore, the solvents of Equation C, supra, are contemplated for the reactions of Equations F, G and H, as well as atmospheric, sub-atmospheric and super-atmospheric conditions. Similarly, an excess of either reactant with respect to the other is contemplated;althoughlstoichiornetric amounts are generally employed. It will be noted from Tables F, G, H (cf, particularly Example LXXI) that tertiary alkyl (lower) amines are likewise contemplated as bases. The amount of base used in the examples of Tables F, G, H is 1 percent, based upon the total weight of reactants l and 2. Generally, from about .01 percent to about 10 percent may be used.

The products of Equations F, G, H are; useful as fire retardants in plastics in the same manner described hereinabove for the products of Equations A, B, C and D.

Clearly, the instant discovery encompasses numerous modifications within the skill of the art. Consequently, while the present invention has been described in detail withrespect to specific embodiments thereof, it is not intended that these details 'be construed as limitations upon the scope of the invention, except insofar as .they

appear in the appended claims. I

We claim: 1- An 'organophosphorus compound of the formula ta nm romornsi awherein R R and R are alkyl C -C3 substituted alkyl C C cycloalkyl, phenyl, substituted phenyl, or naph thy l, said substituents for alkyl being lower alkoxy or cyano'and said substituents for phenyl being lower alkyl or halogen; X is halogen; and R is itrialkylsilylmethylene,

wherein alkyl is C -C 2. The compound of claim 1 wherein R R and R TOBIAS E. LEVOW, Primary Examiner. J. PODGORSKI, Assistant Examiner. 

